1. Field of the Invention
This invention relates to a medicament inhaler, and more particularly to a dry powder medicament inhaler operable with a source of pressurized air to produce a plume of dry powder particles.
2. Brief Description of the Prior Art
Single unit dose dry powder inhaler devices are known, including some which contain multiple chambers and a selector element for releasing a dose from one chamber at a time. Relevant aspects in the designs of these devices include: establishing the correct dosage size in the device; preserving such dose from humidity and other deleterious environment elements; and delivery of the dose in a preferred particulate size within the discharge air flow.
Stated otherwise, the concerns are charging (filling) the device and storage, release, and delivery of the dose. The stored powder is, by necessity, compacted into a very small volume in an essentially solid state capsule. One of the prominent challenges encountered in design of these systems has been the breakup, or deagglomeration, of the aggregate powder dose into a plume of fine particles which are well disbursed in the air flow. Several such devices have been developed which use a variety of methods to accomplish this end.
U.S. Pat. No. 5,694,920 describes an inhalation device. Powdered medicament is stored in a blister well that is carried in a roll housed in a cartridge. Once the blister well is opened, a vibrator deaggregates the powder in the well and keeps the powder in a fluidized state. An electrostatic plate attracts smaller particles of the powder towards the plate, where they are introduced into an air stream and carried toward a mouthpiece.
U.S. Pat. No. 6,026,809 describes an inhalation device that utilizes vibration to facilitate suspension of a powder in a gas. A piezoelectic vibrator is used to vibrate the powder, thereby deaggregating the powder for optimal suspension in an air stream. A controller is provided for controlling the supply of actuating electricity to the vibrator.
U.S. Pat. No. 5,033,463 describes a multi-dose inhaler for medicaments in powder form. The powder is stored in a container in the inhaler. A certain quantity of powder is withdrawn from the container and conveyed to a dispensing position by a cup. A plunger moves the powder from the cup to a mixing unit. Inhalation causes an impeller in the mixing unit to rotate, thereby mixing air and powder before they enter a user""s mouth or nose. Vibrations may be used to facilitate dropping the powder from the container to the cup.
U.S. Pat. No. 6,006,747 describes a dry powder inhaler. The inhaler includes a housing, a cartridge containing medicine supported on the housing, a lid pivotally mounted on the housing, and a mixing chamber. An impeller within the mixing chamber mixes air and the drug before they are inhaled into a patient""s lungs.
U.S. Pat. No. 5,918,594 describes an inhaling device capable of breaking down aggregates of powdered medicament to provide particles within the respiratory range. A magazine contains a dose. A deagglomerating device is disposed in the air flow path of the dose. The deagglomerating device is made of opposing surfaces oriented obliquely to a longitudinal direction of the air flow path. When a patient inhales on a mouthpiece, the dose is drawn through the deagglomerating device.
U.S. Pat. No. 6,003,512 describes an apparatus for aerosolizing and dispensing powders. A dose is placed into a chamber for mixing with pressurized air to break up large particles. The dose may be supplied at each administration, or the apparatus may contain a dose reservoir from which individual doses are supplied to the chamber. The dose mixture is moved through an ejecting conduit and into an exit nozzle. The exit nozzle has a sudden increase in diameter to break the pressurized agglomerates into a fine aerosol.
U.S. Pat. No. 6,029,662 describes a compressed air powder inhaler. Powder is stored in a magazine. Powder from the magazine is mixed with compressed air from an air chamber. The powder is fragmented by the flow of air and then by passing through a grille. The release of the compressed air is triggered by a patient sucking on a mouthpiece.
The present invention is a dry powder inhaler. The inhaler comprises four components: an exit channel, a vibrating means, a dose storage substrate and an air inlet substrate. These four components are stacked together to form the dry powder inhaler. The exit channel is a depression defined in the top surface of the exit channel substrate. The exit channel substrate may have an exit channel per stored dose, or a single exit channel shared by all stored doses. The dose storage substrate has either one, or a plurality of holes, into which a metered dose is stored. From 1 to 350 doses may be individually stored in the dose storage substrate. A vibrating material is placed between the exit channel substrate and the dose storage substrate. An air inlet substrate is positioned above the dose storage substrate. The air inlet substrate may have an air inlet per stored dose, or a single air inlet shared by all the stored doses. A small charge of pressurized air is supplied through the air inlet to the stored dose. The vibrating material deforms due to the air pressure. The powder then exits the inhaler along a trough defined by depression of the vibrating substrate into the exit channel of the exit channel substrate. Air pressure creates a standing wave in the vibrating material that serves to meter the flow of powder from the storage hole, and to deagglomerate and fluidize the stored powder in the air flow.
The present invention overcomes some disadvantages found in prior art inhaler devices, by reducing powder particle size, reducing the occurrence of larger, agglomerated particles, and/or rendering the particles in the flow to be more uniform in size. Furthermore, the present invention accomplishes these ends in an effective, yet simpler and less costly manner when compared to other designs currently available.